The present invention relates to maintaining the on resistance of a power Metal Oxide Semiconductor Field Effect Transistor (MOSFET) on a power path of a portable electronic device at a constant resistance value for current sensing, and more particularly, to an apparatus for performing resistance control on a current sensing component in an electronic device, and an associated method.
According to the related art, a conventional power management integrated circuit (PMIC) in a conventional portable electronic device may be designed to have a power MOSFET on a power path between a battery and a conventional system circuit within the conventional portable electronic device, for selectively enabling or disabling the power path by turning on or off the power MOSFET in different situations. When the power MOSFET is turned on, the on resistance of the power MOSFET may vary with respect to temperature, and therefore can hardly be utilized for current sensing. A conventional method is proposed to maintain the on resistance of the power MOSFET in order to utilize the power MOSFET as a replacement of a conventional current sensing component such as an off-chip current sensing resistor. However, further problems such as some side effects may occur. For example, some additional components implemented for on resistance control according to the conventional method may cause an unstable problem of the conventional PMIC. In addition, the temperature coefficient of the on resistance of the power MOSFET may be impacted by the output performance of one or more of the additional components mentioned above. Thus, a novel architecture is required to control the on resistance of a power MOSFET on a power path within an electronic device at a constant resistance value for current sensing with fewer side effects, and to guarantee the overall performance of the electronic device.